Retracting clamp

ABSTRACT

A retracting clamp for firmly holding work pieces on the bed of a machine tool or the like and incorporating a clamping arm which pivotally releases and linearly retracts inside the body guided by a ball detent in the body which engages a groove in the clamping arm.

United States Patent 1 McPherson 1 Apr. 3, 1973 [.54] RETRACTING CLAMP [75] Inventor: Alexander W. McPherson, Farmington, Mich.

[73] Assignee: Dover Corporation De-Sta-C-Division, Detroit, Mich.

[22] Filed: Sept. 2, 1970 [21] Appl. No.: 69,013

[52] U.S. Cl. ..269/32, 269/93, 269/135 [51] Int. Cl. ..B23q 3/08 [58] Field of Search ..269/32-35, 91-94, 269/239, 134, 135, 25

[56] 7 References Cited UNITED STATES PATENTS 3,381,954 5/1968 Blatt ..269/32 3,565,415 2/1971 Blatt. ..269/32 X 3,567,208 3/1971 Blatt ..269/32 3,482,830 12/1969 Sendoykas... .....269/32 3,572,216 3/1971 Seesody ..269/33 3,578,306 5/1971 Smith ..269/22 X 3,599,957 8/1971 Blatt ..269/32 3,570,835 3/1971 McPherson ..269/32 3,618,931 11/1971 Blatt ..269/32 X Primary Examiner-Robert C. Riordon Assistant Examiner-E. F. Desmond Attorneys-Farley, Forster and Farley [57] ABSTRACT A retracting clamp for firmly holding work pieces on the bed of a machine tool or the like and incorporating a clamping arm which pivotally releases and linearly retracts inside the body guided by a ball detent in the body which engages a groove in the clamping arm.

5 Claims, 4 Drawing Figures PATENTEU APR 3 I973 SHEET 1 BF 2 ATTORNEYS BACKGROUND OF THE INVENTION Power operated clamps utilized for holding work pieces in place on machine tools and the like enable the operator to quickly place a work piece in position and clamp the work piece securely with one or multiple simultaneously actuated power operated holding means. Conventional clamps employ pivoted swinging clamp arms which traverse a wide arc in retracting to a clearance position. Frequently, the work piece configu ration provides limited access to the clamping surface which will not accommodate a full arcuate arm movement for clamping and retraction, but rather includes adequate clearance only for a compound arm movement preferably normal to the clamping surface during final clamping and initial release and generally parallel to the clamping surface for retraction and approach.

SUMMARY OF THE PRESENT INVENTION In the present invention, the clamping arm has an arcuate path provided by spaced actuating and reaction pivots only during final clamping and initial release, a slot for the reaction pivot accommodating linear retraction and approach movement of the clamping arm, and interacting guide means between body and arm assuring such linear movement. A power cylinder has a piston connection with the actuating pivot and complete retraction within the body results in full clearance for workpiece loading and removal. All of the moving parts are located inside of the body of the inside of the body in turn connected with pin 32 to the piston rod 34 of a fluid cylinder formed within the clamp with the exception of the portion of the clamping arm that extends and clamps the work piece in place. The guiding means of the clamping arm which provides the proper motion for extension and retraction of the clamping arm and initiation of the retraction with an unclamping movement is separate from the moving parts of the retracting clamps that undergo the highest loading.

DESCRIPTION OFTHE DRAWINGS FIG. 1 is a side elevation of the retracing clamp;

FIG. 2 is a top cross-section of the retracting clamp taken along the line 22 of FIG. 3;

FIG. 3 is a side cross-section of the retracting clamp, taken along the line 3-3 of FIG. 2; and,

FIG. 4 is a partial section showing the ball detent.

DESCRIPTION OF THE PREFERRED EMBODIMENT In FIG. 1 is shown the body 10 of the clamp comprising two castings l2 and 14 bolted together at 16. Protruding from the end of the retracting clamp body is the clamping arm 18 shown fully extended and lowered into clamping position. The casting 12 includes flanges 20 with holes 22 provided for attachment of the clamp to the base of a machine tool, or the like.

In FIGS. 2 and 3 is shown the interior of the working parts of the retracting clamp. In FIG. 3, a pivot pin 24 engages an elongated slot 26 formed in the portion of the clamping arm located inside of the retracting clamp body 10. The clamping arm 18 thus may either pivot or slide about the pivot pin 24. A second pivot pin 28 connects the clamping arm 18 to yoke elements 30 likewise casting 14 of the body 10. The piston head 36 has a seal 38 and a guide 40 for the piston rod 34. The guide 40 in turn is held in place by snap ring 42. Hydraulic piping may be connected to the threaded hole 44 provided in the end of the casting 14.

To insure the proper motion of the clamping arm, a linear groove 46 with semi-circular cross section is formed in the clamping arm 18 on one side. This groove 46 engages a bearing ball 48 which is part of the ball detent shown in FIG. 4 in fragmentary section. The ball 48 is held properly in position by a spring 50 adjusted by an allenhead set screw 52 and which in turn is accessible from the outside of the retracting clamp body as shown in FIG. I. The groove 46, as shown in FIG. 3, is essentially straight except for a short curved portion 54 fonned in the clamping arm 18 at the inside end of the groove 46. This short curved portion 54 has a radius centered on the center of the pivot pin 24.

In FIG. 3 the motion of the clamping arm is shown by three positions, the solid line 18' fully extended, the dotted line 18" fully retracted and the dashed line 18' raised at the juncture between arcuate and linear movement prior to clamping or retraction. Starting with the fully clamped position, shown by the solid line 18, the curved portion 54 of the groove 46 permits the clamping arm 18 to pivot about the pin 24 as the ac tuating means begins to retract. Once the clamping arm 18 has reached the position shown by the dashed line 18' the ball 48 is in the portion of the groove 46 which joins the curved portion 54 and the clamping arm 18 may retract into the body 10 of the retracting clamp. The groove 46 formed in the clamping am 18 is substantially parallel to the elongated slot 26, thus allowing the retraction of the clamping arm 18 until it reaches a position inside the body 10 shown by the dotted outline 18" of the clamping arm 18. The hole 29 in the clampingarm 18 for the pivot 28 is elongated to provide the necessary freedom of motion for the clamping arm as it pivots about the pin 24.

The movement is reversed when a part is to be clamped into position. The clamping arm 18 moves from the dotted position 18" by extending out to the position shown by the dashed line 18" and then the ball 48 engaging the curved portion of the groove 54 and the pivot pin 24 permit the clamping arm 18 to rotate about the pin 24 to clamp a workpiece in position.

I claim:

1. A retracting clamp, comprising:

a body, a first pivot means in said body, a clamping arm having an elongated slot formed therein and engaging said firstv pivot means, fluid pressure linear actuating means on said body and having a second pivot directly thereattached laterally spaced from said first pivot, said second pivot directly engaging an enlarged hole formed in said clamping arm, a substantially straight groove formed in said clamping arm and having a relatively short arcuate portion at one end thereof, and a ball detent in said body engaging said groove to provide for substantially linear reciprocably extension of said clamping arm followed by a pivotal clamping movement relative to 'a mounting surface for said body.

terconnecting means between the body and clamping arm laterally spaced from said linear actuating means providing for linear motion during said initial movement and a pivotal fulcrum during said rocking movement, one of said connections to said clamping arm including a clearance accommodating simultaneous straight line actuating and menate rocking arm movements. I

5. A retracting clamp as set forth in claim 4 wherein said lost motion means comprises interconnecting slot and pin means. 

1. A retracting clamp, comprising: a body, a first pivot means in said body, a clamping arm having an elongated slot formed therein and engaging said first pivot means, fluid pressure linear actuating means on said body and having a second pivot directly thereattached laterally spaced from said first pivot, said second pivot directly engaging an enlarged hole formed in said clamping arm, a substantially straight groove formed in said clamping arm and having a relatively short arcuate portion at one end thereof, and a ball detent in said body engaging said groove to provide for substantially linear reciprocably extension of said clamping arm followed by a pivotal clamping movement relative to a mounting surface for said body.
 2. The retracting clamp of claim 1 wherein the radial center of said arcuate portion substantially coincides with the axis of said first pivot means.
 3. The retracting clamp of claim 1 wherein said clamping arm reciprocably retracts substantially inside of said body.
 4. A retracting clamp, comprising: a body, a clamping arm, fluid pressure linear actuating means having a piston rod aligned with and pivotally connected directly to said clamping arm adapted to provide initial linear and final rocking movement to the clamping arm, a lost motion interconnecting means between the body and clamping arm laterally spaced from said linear actuating means providing for linear motion during said initial movement and a pivotal fulcrum during said rocking movement, one of said connections to said clamping arm including a clearance accommodating simultaneous straight line actuating and arcuate rocking arm movements.
 5. A retracting clamp as set forth in claim 4 wherein said lost motion means comprises interconnecting slot and pin means. 